Controller for motor driven welder generators



United States Patent 3,041,526 CONTROLLER FOR MOTOR DRIVEN WELDERGENERATORS Ora M. Rybolt, 605 Turrill, Lapeer, Mich. Filed Mar. 31,1959, Ser. No. 803,164 7 Claims. (Cl. 322-85) This invention relates toa control system for an electric welder and more particularly to acontroller for motor driven welder generators.

It is the object of the present invention to provide in conjunction witha motor driven or otherwise power operated welder generator a controlleractivated by the operator and normally at a point remote from thegenera-tor, whereby at the will of the operator the generator voltagemay be increased or decreased.

It is another object to provide a controller including a novelarrangement of relay switches in conjunction with the welder generatortogether with a novel electric circuit interconnecting said relays andwelder whereby the operator may control, either at the generator or at apoint remote therefrom, increases or decreases of the welding voltagesto meet welding conditions.

It is a further object to provide a motor operated rheostat in the fieldcircuit of the exciter generator and welder generator together withmanual control means associated with the welder electrode holder oradjacent the welder generator for selectively rotating the rheostatcontrol in difierent directions for increasing or decreasing theelectrical resistance in said field circuit and correspondingly varyingthe output voltage.

It is a further object to provide electric power to the controllerherein directly from the generator output. Alternately, the power may bedelivered from the exciter generator or from some exterior electricalsource.

These and other objects will be seen from the following specificationand claims in conjunction with the appended drawing in which the figureis a circuit diagram of a conventional welder generator and motoroperated field rheostat, together with a series of relays for regulatingthe generator voltage output.

It will be understood that the above diagram represents a preferredembodiment of the present invention and that other embodiments arecontemplated within the scope of the claims hereafter set forth.

Referring to the drawing there is diagrammatically shown a weldergenerator 1, one of whose brush contacts delivers electrical powerthrough electrode cable 19 to electrode holder 2 and attached weldingelectrode 61. The other brush of the welder generator is grounded at 62.

There is diagrammatically shown an exciter generator 58 and a rotativepower driven shaft 59 for effecting simultaneous rotation of the weldergenerator and said exciter. Shaft 59 may be connected to any source ofrotative power, such as a gas or electric motor or other source.

The generator includes field winding 60, in parallel circuit with fieldwinding 57 of the exciter generator and through leads 28 and 56 isconnected to rheostat 55. Said rheostat includes rotatable contact arm54 secured upon rotative shaft 53 of motor 9. This is a direct currentmotor operating on approximately 28 volts, for illustration.

Terminals 29 and 32 of exciter generator 58 have a difierence inpotential. Field winding 60 is connected in parallel with the armatureof exciter generator 58 through terminal 29, through lead 56 to therheostat 55, through sliding contact arm 54, through 28 to terminal 32,which is the positive side of the potential.

The positive and negative terminals of exciter genera-.

tor 58 furnish the power source to field 60 of the welder m ICCgenerator 1, being regulated by rheostat 55. The field winding 57 ofexciter 58 is also connected in parallel or across the armatureterminals, being a shunt type of generator.

Motor 9 is reversible and in the manner hereafter described under thecontrol of the operator will rotate shaft 53 in one direction or theother through an arc of less than 360 degrees.

If said contact arm rotates clockwise from the position shown, the totalresistance in the rheostat is reduced, reducing the total resistance inthe field circuit and providing an increased welding or output voltage.If contact 54 rotates counter-clockwise, the field resistance increaseswith a corresponding decrease of output voltage from the generator.

The present controller generally indicated within the dotted lineenclosure in the drawing consists of the reversible DC. motor 9 whosedriveshaft 53 is adapted to rotate rheostat contact arm 54 in onedirection or the other. The direction which said shaft will rotate isdetermined depending upon which of the two relays 4 or 5 are energized.

The control of relays 4 and 5 is regulated by ratchet relay assemblygenerally indicated at 3. Said ratchet relay has a magnetic coil 41which when energized draws armature 64 downwardly. Said armaturepivotally mounted at 65, spring-biased at one end at 66 and carries atits other end the spring-biased pivotal pawl 67, adapted on intermittentenergizing of coil 41 to effect increments of rotation of ratchet 68.Its shaft 69 carries rotatable segmented operator 70 controlling themovements of movable contact 23 with respect to spaced contacts 2224.Contact 23, normally biased to contact 24, has an extension 71 operablyengaged by the alternate low and high points on operator 70.

There is also provided a safety relay 10 to selectively bring resistance14 into the circuit when the same is energized during a period of nowelding and to shunt said resistance 14 out during welding.

When welding is being done at electrode 61, motor 9 ,button switch 16,normally spring biased open is depressed into engagement with asuitablecontact in holder 2, the output voltage passes through control wire 18to the plus terminal of said controller. Current is delivered throughbus 27 to safety relay 10. With armature 40 moved downwardly openingcontacts 1213, this elevated voltage in bus 27 passes through resistance14' thereby causing a voltage drop keeping the controller operatingwithin safe limits.

Should the pushbutton 16 be activated during welding, then the outputvoltage through terminal 25 connector 34 and lead 63 will be reduced sothat magnetic coil 39 is ineffective to open contacts 12 and 13. Thusthis reduced output voltage through bus 27 and through contacts 12 and13 is shunted around resistance 14 for direction to leads 27 and 43 foroperating relays 4 and 5.

Should the operator desire to increase or decrease the generator outputvoltage he activates pushbutton switch 16. The output voltage leavingrelay 10 travels through lead 27 through magnetic coil 41 of ratchetrelay 3 to the negative side of the line and returns through lead 42 toterminal 30 on the controller through output terminal 26 of the weldergenerator and is grounded at point 31.

Armature 64 moves downwardly and ratchet 68 rotates a short increment asdoes also the segmented operator 70. The ratchet relay includes movablecontact 23 which is resiliently mounted for selective engagement witheither of contacts 2224 under the control of operator 70, as shown inthe drawing and before energization of coil 41 contact 23 engagescontact 24.

The slight incremental rotation of segment 70 under the action ofratchet 68 on application of switch 16 moves contact 23 from contact 24and into engagement with contact 22.

In this illustration, electrical power is delivered from relay 10through lead 43 to movable contact 23, through contact 22, lead 44,normally closed limit switch 6, and lead 46 for energizing coil 35 ofrelay switch 4, with the circuit completed to the negtaive side throughreturn lead 42 and terminal 26 back to the generator.

The energizing of coil 35 draws the adjacent armature and movablecontact of relay 4, normally spring-biased into engagement with contact37, disengaging the same so that said movable contact engages contact21.

Electrical power from lead 43 from relay 10 is delivered to thestationary contacts 37 and 38 of relay switches 4 and 5. With relay 4energized and contact 37 opened, electrical current from lead 43 travelsvia contact 38 of relay through the normally closed springbiased contactand through lead 48 to reversing switch 50.

In the position shown of said switch, the circuit continues through lead52 to the negative side of direct current motor 9. The circuit iscompleted to said reversing switch through lead 51, and through lead 49,contact 37, contact 21 to the negative side of the line through lead 42.

This, for example, causes motor shaft 53 to rotate clockwise withcorresponding rotation of rheostat control arm 54, decreasing the totalresistance in the generator field circuit and causing an increase of theoutput or welding voltage, for illustration.

Motor shaft 53 continues to rotate in clockwise direction as long asswitch 16 is depressed. Alternately the motor will automatically stop,if switch 16 is not released, when cam 33 engages and opens limitswitchr6. This breaks the circuit to coil 35 deenergizing samepermitting the movable contact of relay 4 to again engage fixed contact37.

In the event, however, that the operator wishes to effect a reducedoutput voltage, he again activates pushbutton switch 16 againmomentarily activating ratchet relay 3 causing ratchet 68 to rotate thedistance of one tooth segment with corresponding rotation of segment 70.This permits movable contact 23 to drop into engagement with contact 24,corresponding to the showing in the drawing.

The circuit is as follows:

Power through lead 43 is through contact 23, contact 24 and lead 45 tonormally closed limit switch 7 through lead 47 to coil 36 of relayswitch 5 energizing the same and returning to the negative side of theline. At the same time electrical power from lead 43 does not leave theopen contact 38 because the movable contact of relay 5 has beenmagnetically opened into engagement with contact 20. However, thecurrent travels to contact 37 of relay switch 4 and through lead 49 tothe opposite side of reverse switch 50..

With said switch in the position shown electrical power travels via lead51 to the plus side of motor 9 and completes circuit to the negativeside through lead 52, the reversing switch 50, lead 48, contact 20 tothe negative side of the line. This causes the DC. motorshaft 53 torotate in a counterclockwise direction with similar rotation of rheostatcontact arm 54 increasing the field resistance. This produces adecreased voltage output for the welded generator. Arm 54 Will continueto rotate but.

less than 360 degrees until the normally open pushbutton switch isreleased. On failure to release said switch manually, the motorshaftwill continue to rotate in a counterclockwise direction until cam 33 onthe shaft engages and opens the normally closed limit switch 7 breakingthe electrical circuit to coil 36 of relay 5, causing the motor to stop.

If the first activation of pushbutton switch .16 produces an increase ofvoltage when a decrease is desired, all that is necessary is to manuallyrelease pushbutton switch 16 and to again activate the same to reversethe direction of rotation of motorshaft 53.

Simply speaking, pushbutton switch 16 causes the motorshaft to rotate inone direction or the other. Each time the switch 16 is activated theratchet '68 is rotated one segment. Thus successive activation ofpushbutton switch 16 causes intermittent rotation clockwise of thesegment 79, intermittently switching the connections of contact 23 withrespect to the contacts 22--24 in relay 3. This provides a means ofintermittently activating either relay switch 4 or 5 with correspondingrotation of motorshaft 53 in one direction or the other.

The purpose of reversing switch 50 is that when the motor direction ischanged, the respective limit switches 6 and 7 will operate on the rightside so as to open the proper contacts of relay 4 or 5 depending uponthe polarity of the current applied to the armature of the permanentmagnate field of motor 9 and contacts 22, 23, 24 of relay 3.

Said reversing switch provides proper contact with limit 6 7 so thatwhen polarity changes, the right polarity is applied to the armature ofmotor 9 so that the circuit will be interrupted, stopping the motor whencam 33 engages either of the contacts 6 or 7.

As above described, during a welding operation, the voltage outputthrough lead 63 to the coil of relay 10 drops below 45 volts andcontacts 12 and '13 are permitted to close or stay closed shorting outresistance 14 and allowance the operation of the controller to takeplace at the lower voltage.

Pushbutton switch l15 is also provided on said controller between busline 27 and lead 63. By closing switch 15 motor 9 may be operated toregulate rheostat 55, thus enabling the operator to change outputvoltage at the controller without utilizing switch 16. Intermittentactivation of either switch 15 or 16 will operate motorshaft 53alternately in opposite directions as above described.

In operation, when pushbutton 15 or 16 is depressed, motor 9 will run inone direction until it is stopped by one of the limit switches 6 or 7depending upon contacts 22, 23, 24 of ratchet relay 3. By releasingpushbutton 15 or 16 and depressing it again, the motor 9 coupled torheostat 55 will run in the opposite direction and it continued, theoperation will be interrupted by limit switch 6 or 7.

When either of the pushbutton switches 15-16 is opened a spark ispresent upon opening of the contacts. Condenser 17 is connected betweencontrol wire 18 and the output terminal 2563. This reduces sparking to aminimum,

The present controller is operated by power taken from terminals 25-26of the welder generator 1 as shown by the solid lines in the drawing. Itis contemplated that the controller may be powered and operated frompower taken from terminals 29 and 32 of the exciter generator, byremoving cable 26 between terminal 30 on the controller and terminal 31on the Welder generator. At the same time a line is connected betweenterminals 29 and 30 as shown by dotted line 72. Also the electrode cable19 is connected to terminal 32 on the exciter generator by an additionallead shown in dotted lines at 73.

It is furthermore understood that said controller may be operated by anexternal source of power and connected as shown by the dotted lines. Itis contemplated also that the welder generator may be operated by anysource of prime mover applied to rotatable shaft 59. The presentcontroller may operate on gas and electric driven welders and on mostrectifier welders with good results.

Having described my invention, reference should now be had to thefollowing claims.

I claim:

1. In a welder a generator adapted for connection to a rotative powerdrive, having a power output line and a field winding, an exciter havinga field winding in parallel circuit with said generator field winding, avoltage controller for said generator consisting of a rheostat withrotatable contact connected in series with said generator, wherebyrotation in one direction of said contact increases and in the oppositedirection decreases the welding voltage, a motor having an output shaftjoined to said rheostat contact, an electrical circuit connecting thegenerator power output line to said motor in driving relation, andswitch means including a normally open manual switch in circuit withsaid output line and motor for intermittently energizing said motor foralternate rotary movements of its output shaft in opposite directions,said switch means including a pair of normally closed relays in saidcircuit respectively connecting the generator output line to oppositepoles of said motor, and an impulse relay in circuit with said generatoroutput line, manual switch and normally closed relays for alternatelyopening one of said normally closed relays on activation of said manualswitch.

2. In a welder a generator adapted for connection to a rotative powerdrive, having a power output line and a field winding, an exciter havinga field winding in parallel circuit with said generator field winding, avoltage controller for said generator consisting of a rheostat withrotatable contact connected in series with said generator, wherebyrotation in one direction of said contact increases and in the oppositedirection decreases the welding voltage, a motor having an output shaftjoined to said rheostat contact, an electrical circuit connecting thegenerator power output line to said motor in driving relation, andswitch means including a normally open manual switch in circuit withsaid output line and motor for intermittently energizing said motor foralternate rotary movements of its output shaft in opposite directions,said switch means including a pair of normally closed relays in saidcircuit respectively connecting the generator output line to oppositepoles of said motor, a magnetic coil for each relay, and an impulserelay in circuit with said generator output line, manual switch andcoils selectively for alternately energizing one of said coils onactivation of the manual switch for driving said motor in one direction.

3. In a welder a generator adapted for connection to a rotative powerdrive, having a power output line and a field winding, an exciter havinga field winding in parallel circuit with said generator field winding, avoltage controller for said generator consisting of a rheostat withrotatable contact connected in series with said generator, wherebyrotation in one direction of said contact increases and in the oppositedirection decreases the welding voltage, a motor having an output shaftjoined to said rheostat contact, an electrical circuit connecting thegenerator power output line to said motor in driving relation, andswitch means including a normally open manual switch in circuit withsaid output line and motor for intermittently energizing said motor foralternate rotary movements of its output shaft in opposite directions,said switch means including a pair of normally closed relays in saidcircuit respectively connecting the generator output line to oppositepoles of said motor, a

magnetic coil for each relay, and an impulse relay in circuit with saidgenerator output line, manual switch and coils selectively foralternately energizing one of said coils on closing of said manualswitch for driving said motor in one direction, a successive closing ofsaid manual switch energizing said impulse relay to alternately energizethe other of said coils for driving said motor in the oppositedirection.

4. In a welder a generator adapted for connection to a rotative powerdrive, having a power output line and a field winding, an exciter havinga field winding in parallel circuit with said generator field winding, avoltage controller for said generator consisting of a rheostat withrotatable contact connected in series with said generator, wherebyrotation in one direction of said contact increases and in the oppositedirection decreases the welding voltage, a motor having an output shaftjoined to said rheostat contact, an electrical circuit connecting thegenerator power output line to said motor in driving relation, andswitch means including a normally open manual switch in circuit withsaid output line and motor for intermittently energizing said motor foralternate rotary movements of its output shaft in opposite directions,said switch means including a pair of normally closed relays in saidcircuit respectively connecting the gen-.

erator output line to opposite poles of said motor, a magnetic coil foreach relay, an impulse relay in circuit with said generator output line,manual switch and normally closed relays for alternately energizing oneof said coils on closing of said manual switch for driving said motor inone direction, a pair of spaced normally closed limit switchesrespectively connected to each magnetic coil, and a cam on said motoroutput shaft spaced between said limit switches on predeterminedrotation thereof, engageable with a limit switch for de-energizing saidmotor.

5. In a welder a generator adapted for connection to a rotative powerdrive, having a power output line and a field winding, an exciter havinga field winding in parallel circuit with said generator field winding, avoltage controller for said generator consisting of a rheostat withrotatable contact connected in series with said generator, wherebyrotation in one direction of said contact increases and in the oppositedirection decreases the welding voltage, a motor having an output shaftjoined to said rheostat contact, an electrical circuit connecting thegenerator power output line to said motor in driving relation, andswitch means including a normally open manual switch in circuit withsaid output line and motor for intermittently energizing said motor foralternate rotary movements of its output shaft in opposite directions,said switch means including a pair of normally closed relays in saidcircuit respectively connecting the generator output line to oppositepoles of said motor, a magnetic coil for each relay, an impulse relay incircuit with said generator output line, manual switch and normallyclosed relays for alternately energizing one of said coils on closing ofsaid manual switch for driving said motor in one direction, said impulserelay including a pair of spaced contacts respectively connected to saidcoils, an intermediate power delivery contact engageable with one ofsaid spaced contacts, and a coil and armature ratchet means onintermittent closing of said manual switch alternately and successivelyconnecting said power contact with said spaced contacts respectively.

-6. In a welder a generator adapted for connection to a rotative powerdrive, having a power output line and a field winding, an exciter havinga field winding in parallel circuit with said generator field winding, avoltage controller for said generator consisting of a rheostat withrotatable contact connected in series with said generator, wherebyrotation in one direction of said contact increases and in the oppositedirection decreases the welding voltage, a motor having an output shaftjoined to said rheostat contact, an electrical circuit connecting thegenerator power output line to said motor in driving relation, andswitch means including a normally open manual switch in circuit withsaid output line and motor for intermittently energizing said motor foralternate rotary movements of its output shaft in opposite directions,asafety relay including a magnetic coil in closed circuit with saidgenerator output line, an electric resistance, and a pair of normallyclosed contacts shunting out said resistance on closing of said manualswitch during welding, the closing of said manual switch with no weldingproviding an increased voltage to said magnetic coil opening saidcontacts.

7. In a welder a generator adapted for connection to a rotative powerdrive, having a power output line and a field Winding, an exciter havinga field winding in parallel circuit with said generator field Winding, avoltage controller for said generator consisting of a rheostat withrotatable contact connected in series with said generator, wherebyrotation in one direction of. said contact increases and in the oppositedirection decreases the welding voltage, a motor having an output shaftjoined to said rheostat contact, an electrical circuit connecting thegenerator power output line to said motor in driving 20 relation, andswitch means including a normally open manual switch in circuit withsaid output line and motor for intermittently energizing said motor foralternate rotary movements of its output shaft in opposite directions,

said switch means including a pair of normally closed relays in saidcircuit respectively connecting the generator output line to oppositepoles of said motor, a magnetic coil for each relay, an impulse relay incircuit with said generator output line, manual switch and normallyclosed relays for alternately energizing one of said coils on] closingof said manual switch for driving said motor in" one direction, a safetyrelay including a magnetic coil in closed circuit with said generatoroutput line, an elec tric resistance, and a pair of normally closedcontacts with no welding providing an increased voltage to said magneticcoil opening said contacts.

References Cited in the file of this patent UNITED STATES PATENTS922,219 Volkenburg May 18, 1909 1,736,471 Wagner et al. Nov. 19, 19292,140,351 De Croce Dec. 13, 1938 2,305,206 Strobel Dec. 15, 19422,438,634 Farrow Mar. 30,1948 2,642,515 Bagg June 16, 1953

